package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

/**
 * @Description: TODO
 * @Author: Yang
 * @DateTime: 2023/5/16 16:33
 **/
@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }

    public void setWithLogicalExpire(String key,Object value,Long time,TimeUnit unit){
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }

    public <R, ID> R queryWidthPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID ,R> dbFallback,Long time,TimeUnit unit
    ){
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)) {
            return JSONUtil.toBean(json, type);
        }
        if(json != null){
            return null;
        }
        R r = dbFallback.apply(id);
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        this.set(key,r,time,unit);
        return r;
    }

    public static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    //逻辑过期方式，解决缓存击穿
    public <R, ID> R queryWithLogicalExpire(String keyPrefix,ID id,Class<R> type,Function<ID, R> dbFallback,Long time,TimeUnit unit){
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(json)) {
            return null;
        }
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        if(expireTime.isAfter(LocalDateTime.now())){
            return r;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        if (isLock) {
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    R r1 = dbFallback.apply(id);
                    setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unLock(lockKey);
                }
            });
        }
        return r;
    }

    //获取锁
    public Boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    //释放锁
    public void unLock(String key){
        stringRedisTemplate.delete(key);
    }
}
